Canon XC
We have received from our divine Fathers the canon law that in honour of Christ’s resurrection, we are not to kneel on Sundays. Lest therefore we should ignore the fulness of this observance we make it plain to the faithful that after the priests have gone to the Altar for Vespers on Saturdays (according to the prevailing custom) no one shall kneel in prayer until the evening of Sunday, at which time after the entrance for compline, again with bended knees we offer our prayers to the Lord. For taking the night after the Sabbath, which was the forerunner of our Lord’s resurrection, we begin from it to sing in the spirit hymns to God, leading our feast out of darkness into light, and thus during an entire day and night, we celebrate the Resurrection.
From the evening entrance of the Sabbath until the evening entrance of the Lord’s day there must be no kneeling.
No doubt the synod by the words “we have received from the divine Fathers,” referred to canon xx. of the Council of Nice.
p. 404 For many centuries this custom was preserved even in the Latin Church; and the custom of keeping feasts and whole days generally from evening to evening is believed to have been an Apostolic tradition, received by them from the Jews. At the end of the VIIIth Century the Synod of Frankfort declared in its xxj. canon, that “the Lord’s day should be kept from evening to evening.” 385